Address token refresh with {httr2} upgrade

[zacdav-db]

References:

• fix(db_perform_request/response): refresh bearer token manually with margin #254
• Allow configuring when OAuth tokens are treated as expired r-lib/httr2#860
• Allow configurable OAuth expiry margins r-lib/httr2#861

Will need to wait for CRAN release of {httr2}

cc: @max607

[zacdav-db]

{httr2} 1.3 is now on CRAN and therefore this can be addressed.